For its high efficiency, energy-savings, and other advantages, light-emitting diode (LED) lighting is a prominent technology in the field of lighting. In replacing the traditional incandescent lighting which LED lighting, silicon-controlled rectifier (SCR) circuits may be used to achieve precise dimming of an LED load. In conventional approaches, an LED driving circuit with an SCR typically controls a switching operation of a power switch in a power stage circuit, and provides a constant output current for the LED load. Commonly, the LED driving circuit has power factor correction (PFC) function to maintain an input current phase that is consistent with an input voltage of the power stage circuit.
FIG. 1 shows waveforms of example input voltage current of the LED driving circuit with an SCR in conventional approaches. The SCR can be turned off when the input current of the power stage circuit is less than a holding current of the SCR. However, because the input voltage is not zero at this time, the SCR trigger circuit may charge the SCR to conduct. Then, oscillation may be generated on the input current as shown in FIG. 1. This can cause the SCR to re-conduct irregularly for many times, such that the LED driving circuit may absorb different power from the input side in each period. As a result, the LED light load may experience different brightness in different periods, as well as LED flicker and noise.